1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a system and method in a General Packet Radio Service (GPRS) network for interfacing a Base Station System (BSS) with a Serving GPRS Support Node (SGSN).
2. Description of Related Art
The Gb interface is an interface in the GPRS network between the SGSN and the BSS. Currently, the Gb interface sets up virtual circuits between the SGSN and the BSS based on the connection-oriented Frame Relay protocol. The protocol stack currently comprises an L1 physical layer (related to Frame Relay), a Network Service (NS) layer, and a Base Station System GPRS Protocol (BSSGP) layer. The NS layer is divided into two sub-layers. The upper NS sub-layer is called the Network Service Control (NSC), and is like the glue with the BSSGP layer above. The lower NS sub-layer is called Sub-Network Service (SNS), and is like the glue with the underlying Frame Relay structure. The structure and function of the existing layers is described in more detail below in connection with FIGS. 1 and 2.
It is desirable to replace existing interfaces in the GPRS network with connectionless Internet Protocol (IP)-based interfaces. Currently, for example, the interface between the SGSN and the Gateway GPRS Service Node (GGSN) is based on IP, and many of the network nodes operate internally on the IP protocol. Many advantages could be gained by converting the Gb interface to utilize IP also. A straightforward solution is to encapsulate the Frame Relay information in IP packets sent between the two nodes. However, this solution adversely impacts the performance of the Gb interface as described further below. Also, there are existing networks using the Gb interface over Frame Relay, and any new interface needs to be backward compatible to support these Frame Relay networks. Therefore, the new interface must have a protocol stack that supports both Frame Relay and IP. Thus, unlike other interfaces in the GPRS network, the Gb interface has not been converted to IP because there has not been a solution identified that supported both Frame Relay and IP while not adversely affecting the performance of the interface.
It would be advantageous to have a system and method for interfacing the BSS and the SGSN that is based on the IP protocol. Basing the interface on IP would provide additional flexibility and features that exist in IP but not in Frame Relay. There is also a larger pool of products available for IP than for Frame Relay, and the use of IP allows the use of several different layer 1 and layer 2 technologies (e.g., Frame Relay, Ethernet, fiber optics, etc.). In essence, the Gb interface would become carrier-independent and much more flexible in terms of routing. It would also be easier to maintain.
There are no known prior art teachings or suggestions of a method such as that described and claimed herein.
In one aspect, the present invention is a method in a General Packet Radio Service (GPRS) network of interfacing a Base Station System (BSS) and a Serving GPRS Support Node (SGSN). The method implements a protocol stack in the BSS and the SGSN that includes a User Datagram Protocol (UDP) layer over an Internet Protocol (IP) layer. Data packets are then transmitted between the BSS and the SGSN over a connectionless IP network. The data packets carry information between functional entities in the SGSN and functional entities in the BSS.
The protocol stack includes a Base Station System GPRS Protocol (BSSGP) protocol layer that provides radio-related, Quality-of-Service (QoS), and routing information that is required to transmit user data between the BSS and the SGSN. The stack also includes a modified Network Services (NSxe2x80x2) layer which is divided into an upper NSxe2x80x2-Network Service Control (NSxe2x80x2-NSC) sub-layer and a lower NSxe2x80x2-Sub-Network Service (NSxe2x80x2-SNS) sub-layer. The NSxe2x80x2-NSC sub-layer maps to the BSSGP layer and manages functional entities therein. The NSxe2x80x2-SNS sub-layer maps to the UDP and IP layers and provides access to the IP network. A single UDP port is reserved to make the NSxe2x80x2 layer and the BSSGP layer act as an application over the IP stack.
In another aspect, the present invention is an SGSN that interfaces with a BSS utilizing a Gb-over-IP interface. The SGSN includes a protocol stack that includes a UDP layer over an IP layer, and means for transmitting and receiving packet data units (PDUs) to and from the BSS over a connectionless IP network.
In yet another aspect, the present invention is a BSS that interfaces with an SGSN utilizing a Gb-over-IP interface. The BSS includes a protocol stack that includes a UDP layer over an IP layer, and means for transmitting and receiving PDUs to and from the SGSN over a connectionless IP network.
In still another aspect, the present invention is a system for interfacing an SGSN with a BSS utilizing a Gb-over-IP interface. The system comprises an SGSN and a BSS which are modified to utilize the Gb-over-IP interface. The SGSN includes a protocol stack that includes a UDP layer over an IP layer, and means for transmitting and receiving PDUs to and from the BSS over a connectionless IP network. The BSS includes a protocol stack that includes a UDP layer over an IP layer, and means for transmitting and receiving PDUs to and from the SGSN over the connectionless IP network.